I use hot glue. It is easy,cheap and flexible it will fix little holes or cracks in your car body its clear and nobody will even see it.
You can either cut out the front windscreen or you can drill some holes in windscreen.After you cut or drill out your windscreen get a fine file and file of the sharp edges.Trim the body around the engine head and the carburetor area. This area needs to be cut large enough to allow easy access for the glow plug igniter, and to adjust the needle valve. It also has to clear the cylinder head.
Remember you want to keep the engine running as cool as possible
Squeeze a tiny dab of silicone in the screw hole it wont destroy plastic and it is easy to undo it if you need to take the screw out again but it stops your screws coming loose and falling out.
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